Apparatus for controlling the release of bombs from aircraft



Oct. 7, 1947. E. s. PETERSON 2,423,531

APPARATUS FOR CONTROLLING THE RELEASE 0F BOMBS FROM AIRCRAFT Filed July 18, 1942 5 Sheets-Sheet 1 ALJ m m 1 35 w A $558 23 m w p z: QE 5 55% r. 8d: 93 5,218.2 z: 5 we 9 7 W 8. 2252 M23: 28 H w J E Ne w 5 we 3 =5: 3

Oct. 7, 1947. E. s. PETERSON APPARATUS FOR CONTROLLING THE RELEASE OF BOMBS FROM AIRCRAFT Filed July 18, 1942 5 Sheets-Sheet 2 N w 53 n l f a 55mm W H NQN ETAWM 3 n 252. 2w- :25 m J r. w m -3 .r w |H.Y f zm a 08 38% 8 g M a new; mmw o 3? an 3 EIL r 5 2% N8 wk a d 1 8 555250 fif S3 QQL wfiafifiw 5N M2282 E 23 H. mm 8- Q E c- BNIIMKPIIIKN w an 2:? 5228: 7H 8 w 55% 2% Mi m M ATTORNEYS Oct. 7, 1947. E. s. PETERSON 2,428,581

APPARATUS FOR CONTROLLING THE RELEASE OF nouns mom AIRCRAFT Filed July 18, 1942 5 Sheets-Sheet 3 FIG. 3

, INVENTOR.

EDWARD S. PETERSON ma M m ATTORNEYS ,Oct. 7, 1947. E. s. PETERSON APPARATUS FOR CONTROLLING THE RELEASE OF BOMBS FROM AIRCRAFT Filed July 18, 1942 5 Sheets-Sheet 4 oom Oct. 7, 1947. E. s. PETERSON 2,428,581

APPARATUS FOR CONTROLLING THE RELEASE OF BOMBS FROM AIRCRAFT Filed July 18, 1942 5 Sheets-Sheet 5 FIG. 5

FIG. 6

INVENTOR EDWARD S. PETERSON ATTORNEYS V Patented Oct. 7, 1947 APPARATUS FOR CONTROLLING THE RE- LEASE OF BOMBS FROM AIRCRAFT Edward S. Peterson, Elmwood Park, Ill., asslgnor to Automatic Electric'Laboi-atories, Inc., a corporation of Delaware Application July 18, 1942, Serial No. 451,513

9 Claims. (01. 177-380) The present invention relates to apparatus for controlling the release of bombs from an aircraft and, more particularly, to improvements in apparatus for so timing the release of bombs from an aircraft that a predetermined spacing between bomb hits on an objective may be obtained.

In certain bombing operations the maximum effectiveness is obtained by releasing the bombs in trains and at spaced intervals, such that a predetermined spacing interval between hits on the objective is obtained. For example, in bombing troop columns, supply trains or the like, the maximum destructive power is obtained by releasing the bombs at such intervals that the zone of destruction of one exploding bomb of the train just overlaps the zone of destruction of the preceding and succeeding bombs cf the train. The spacing between hits on such an objective is, of course, determined by the ground speed of the aircraft from which the bombs are released and the time interval separation between the release of successive bombs of the train. To correlate these factors so that any desired spacing interval between bomb hits on the objective may be obtained while the aircraft is traveling at a predetermined but variable speed, it is necessary to provide a device for measuring the time interval between the release of successive bombs of the train. Such a device must be readily adjustable to vary the measured time intervals so that any desired spacing between bomb hits on the objective may be obtained at any ground speed of the craft from which the bombs are released.

It is an object of the present invention to provide electrical timing apparatus of the character described, which is of simple and rugged construction, is easy to adjust and operate, is thoroughly reliable in operation at any air pressure and under widely varying temperature conditions, and is light in weight.

According to another object of the invention, provisions are made in the apparatus for preventing variations in the timing operations of the apparatus regardless of wide variations in the voltage of the current supply source from which the component parts of the apparatus are energized.

In accordance with a further object of the invention, improved facilities are provided in the apparatus for insuring the start of the bomb release operations within a short predetermined time interval after the bomb release key, button or other device is operated.

According to still another object of the invention, provisions are made in the apparatus for adjusting the circuit equipment to obtain a desired uniform ratio between the bomb release intervals and the bomb spacing intervals, regardless of the periodicity of bomb release and regardless of manufacturing variations in the component parts of the circuit equipment.

It is a further object of the invention to provide improved apparatus of the character described. which includes a presettable device for terminating the bomb release operations after a predetermined number of bombs, determined by the setting of the device, have been releasd.

It is still another object of the invention to provide, in combination with the bomb spacing interval control element of the apparatus, improved indicating facilities which are so arranged that for any setting of the control element the relationship between the ground speed of the aircraft and the spacing between bomb hits on the objective is clearly indicated thereby.

The invention, both as to its organization and method of operation, together with further ob- Jects and advantages thereof, will best be understood by reference to the specification taken in connection with the accompanying drawings in which Fig. 1 illustrates the circuit arrangement of improved bomb release timing apparatus, characterized by the features of the present invention; Fig. 2 illustrates a modification of the circuit arrangement shown in Fig. 1; and Figs. 3, 4, 5 and 6 illustrate the mechanical construction and arrangement of improved apparatus which may be wired either in accordance with the circuit shown in Fig. 1 or the circuit shown in Fig. 2.

Referring now more particularly to Fig. 1 of the drawings, there is schematically illustrated a bomb release mechanism I of the electroma netically controlled type now in use on modern bombing planes. Without regard to the mechanical construction of this mechanism, it may be pointed out that the mechanism is adapted successively to release a train of bombs from the bomb bay of the plane in which it is mounted, in response to a train of current impulses of corresponding numerical value. More specifically, the arrangement of the mechanism is such that one bomb is released thereby in response to each received current impulse and the periodicity of the received impulses may be varied to correspondingly change the rate at which the bombs are released thereby. The arrangement of the mechanism may be such that the spacing interval between the release of any two bombs of the train is determined either by the open-circuit or the closed-circuit period of the impulse. In general, however, the mechanism is so designed that for reliable operation the received impulses should be divided equally as between the make and break periods thereof, this being true regardless of the periodicity of the received impulses in a train.

In general, the improved apparatus for controlling the transmission of impulses to the release mechanism l85 comprises a control tube I00 having a timing network, which comprises the aeepci well known pentode type having an anode time,

a cathode tube, a cathode heater itch, a control grid mils and a screen electrode lots. Preferably this tube is oi the well known commercial 251.6 type. The characteristics of this tube are such that ii a constant potential is maintained upon the screen electrode thereof and the bias voltage impressed between the input electrodes time and Mills is maintained at a fixed value, the space current flow therethrough is held substantially constant regardless of wide variations in the voltage applied to the anode itillc thereof.

Stated in other terms. the characteristics of the tube are such that by holding the potential oi the screen electrode M lls constant, wide variations in the voltage applied to the anocle toilet do not produce any substantial variation in the space current flow through the tube. purpose of maintaining the potential applied to the screen electrode Wits substantially constant regardless oi wide variations in the voltage ap pearing across the output terminals of the source 1165, a voltage regulating arrangement is provideci which comprises a gas filled electric dis charge tube tilt shunting the output terminals oi the source its in series with the voltage regulat= ing resistor its. The tube tilt which may be of the well known neon type, for example, has the characteristic of maintaining a substantially constant voltage across its electrodes regardless oi the magnitude of space current flow therethrough after the gas surrounding these electrodes is ionized to provide a conductive space current path. This tube as provided in the illustrated circuit is designed to have a normal operating voltage which approximates the normal screen voltage rating of the tube Wu. In order to render the operation of the apparatus substantially inde-- pendent of variations in the ambient temperature, a resistor Hi2 having a negative temperature coefficient of resistance is provided in the timing network. This resistor, whose resistance decreases with rising temperature, has the effect of compensating or ofisettlng changes in the rate at which impulses are produced by the apparatus which would otherwise be caused by large changes in the temperature of the other circuit elements. Although any carbon or ceramic'resistor having the proper negative temperature coefilcient of resistance may be used, the resistor I 02' is preferably of the type manufactured by the Keystone Carbon Company, Inc, of Saint Marys, Pennsylvania, having a negative temperature coefflcient at centigrade of 0.02 ohm/ohm/ centigrade.

The arrangemen of the illustrated apparatus is such that the mb release mechanism I85 may be manually controlled by the bomb release switch I61 to release the bombs held in the bomb bay of the craft one at a. time, or automatically controlled to release a. number of bombs in a. predetermined train. To this end, a control switch III! is provided. This switch is of the snap-acting type and is provided with three positions, i. e.,

train of bombsin response to one operation of For the the switch it'i, and a select position wherein the apparatus is conditioned to release a single bomb in response to each operation of the switch itl. In order visually to indicate to a bombarclier that the switch i to has been operated to its train position, a signal lamp it'll is provided.

For the purpose of counting the released bombs of a train and, more specifically, that of counting the impulses transmitted by the pulsing relay sec to the bomb release mechanism 685, a presettable counting device Ht is provided. This device may be preset to cause the release of any desired number of bombs in a train and, operating in conjunction with the locking relay M8, is arranged to terminate the transmission of im pulses to the bomb release mechanism 6% after bombs, corresponding in number to the setting of the device, have been released by this mechanism. in order to initiate the operation oi the apparatus to cause the release of a train oi bombs at the exact instant that the bombsight is brought to bear upon the leading end oi. an objective, the button or hey-operated, self-restoring switch it? is provided. Current for energizing the control elements of th bomb release mechanism tilt, the windings of the relays MED and 11%, the stepping magnet ills of the counting device till, the cathode heater iililh, and. the filament of the signal lamp i3? is cleriveci from a current source its. For convenience in describing the circuits, this source is shown as a battery. lnpractice, how'- ever, this source may comprise a small motor driven generator having an output voltage that may vary over rather wide limits. This source may, in the usual installation, have a voltage rating of approximately 26 volts, with an expected variation in this voltage of from as to 28.5 volts. if desired, a power switch Etta may be provided for disconnecting the positive or ungrcunded terminal of this source from the illustrated circuit apparatus. The indicated screen and anode voltage source M35 is, in efiect, a voltage step-up device having its input terminals ictlc arranged to be connected across the terminals of the current source We. This device is preferably of the mechanical vibrator type having an input voltage rating equal to that of the source B68 and an output voltage rating of approximately 200 volts. Forthe purpose of smoothing the direct output voltage appearing across the output terminals I?) thereof, a condenser IE6 is connected in shunt with these terminals.

As shown in Figs, 3, 4, 5 and 6 of the drawings, most of the above-described parts of the apparatus are supported upon a, chassis which comprises a front panel 800 and an inwardly disposed subpanel 3M, the two panels being held in spacedapart relationship by means of columns 533 pro- Jecting inwardly from the front panel 300, and being secured together by means of assembly screws 534. The various parts of the apparatus are housed within a case 400 upon which the front panel 300 is mounted by means of suitable mounting screws. More specifically considered, the above-identified parts of the apparatus are directly supported upon the sub-paneliIlI. This subpanel also carries sockets ior receiving the control tube I00, the-electric discharge tube I38 and the signal lamp I31 together with an outlet socket 302 through'which connections may be brought out to the current supply source I88 and the contact springs of the bomb release switch I61.

Briefly to consider the mechanical construction and arrangement oithe counting ,devicel'lll, the details. of which arebest shown in Fig. .3 0t

the drawings, it will be noted that this device comprises a frame Ia upon which the spring pile-up I13 is mounted. One of the movable contact springs of this pile-up is provided with a cam finger I13a which is normally engaged by a control pin I12 to maintain the movable and stationary contacts carried by the springs of the pile-up out of engagement. The pin I12 is carried by a detent wheel I1I which is rotatable with the ratchet wheel I14 and a stub shaft I14a rotatably mounted on the frame I10a. Rotation may be imparted to the shaft HM and the two wheels I14 and "I under the control of the pulsing relay I50 by means of the stepping magnet I15 acting in conjunction with the illustrated pawl mechanism. More specifically, the magnet I15'is carried by the frame "011 and is provided with an armature I16 which carries at the upper end thereof a pawl member I11. This pawl member is mounted on a pivotpin I18 extending between the inturned ends of the armature I16, and is provided with a stop part I11a which is spring biased to engage the left edge of the frame projection I19. The pawl finger of the member I11 is normally restrained out of the path of rotation of the teeth on the ratchet wheel I14 by means of a leaf spring I80 which is secured flatwise against the outer surface of the armature I16 and is provided with an extended portion that engages the edge of the frame projection I19 opposite that engaged by the pawl member part "111. From the above explanation it will be understood that each time the magnet I15 is energized to attract its armature I16, this armature is pivoted in a counterclockwise direction, as viewed in Fig. 3 of the drawings, against the bias of the leaf spring I80. Incident to this operation the pawl member I11 is pivoted and translated until the pawl finger thereof engages one of the teeth of the ratchet wheel I14. Continued movement of the armature I1'6 toward the pole face of the magnet I15 serves to rotate the shaft H411 and connected wheels I14 and HI in the clockwise direction. The detent wheel I1I is provided for the purpose of insuring a precise and predetermined movement of the pin I12 in response to each operation of the magnet I15 and the associated pawl mechanism. To this end a centering spring "la is provided which is anchored at one end to the frame NM. The free end of this spring is provided with a return bent portion shaped accurately to conform to the tooth configuration of the teeth on the detent wheel I1I. By virtue of the arrangement of the detent wheel "I and the coacting centering spring I1Ia, this wheel and the pin I12 carried thereby are moved through the same predetermined angle in response to each energization of the stepping magnet I15, regardless of the length of the stroke imparted to the armature I16.

In performing a given counting operation, the device I10 functions to count the number of steps required to return the pin I12 from a preselected off-normal position to its normal position wherein it engages the cam follower portion I13a of one of the movable springs in the spring pile-up I13. In order to rotate the wheels I14 and "I for the purpose of presetting the pin I12 to a desired off-normal position, the shaft "411 is provided with a portion which extends through openings provided in the two panels 30I and 300 and has mounted thereon a knob IBI. This knob carries an indexing element IBIa which, in cooperation with a circular scale 403 inscribed or otherwise formed on the outer surface of the panel 30I, forms a convenient arrangement for indicating the setting of the pin I12. More specifically, the indicia of the scale 403 are suitably arranged to indicate the number of bombs which will be released during a given counting operation before the bomb release operations are terminated. In this regard it will be understood that since the finger of the pawl member I11 is normally held out of engagement with the teeth of the ratchet wheel I14, this wheel and the detent wheel "I may be rotated in either direction by suitable manipulation of the knob I8I.

The mechanical construction and arrangement of the rheostat I02 and the indicating means associated therewith is best illustrated in Figs. 1, 5 and 6 of the drawings. This rheostat is provided with a supporting structure comprising three panels 500, 5M and 502, and a camming plate 503 which are mounted in spaced-apart relationship by means of the spacing columns 504, 505 and 505 and the assembly screws 509 and 5I0. The three panels are constructed of insulating material such as fiber or the like and carry the electrical fixtures of the device. More specifically, the panel 50I carries a number of spaced-apart contact pieces I3I which are concentrically mounted about the center of the panel and are provided with inwardly disposed contact points which are adapted to be engaged by the end of a wiper I29 mounted for rotation with the operating shaft 520 of the device. The panel 502 similarly supports a number of contact pieces I32 having contact points arranged to be engaged by the end of a wiper I30 which is mounted for rotation with the operating shaft 520 of the device. As schematically indicated in Fig. 1 of the drawings, the contact pieces I3I and I32 are radially staggered about the axis of the shaft 520 while the contact making ends of the wipers I29 and I30 are in axial alignment. With this arrangement, and during rotation of the shaft 520, the contact pieces I3I and I32 are .alternately engaged by their respective associated wipers I29 and I30. The two center panels MI and 502 also carry terminal pieces 5I3 and SM, respectively, which are provided with inwardly extending contact making ends that are biased to engage collector rings 5I6 and SH! mounted for rotation with the shaft 520. In the illustrated wiring arrangement these two terminal pieces are connected together and to the control grid of the control tube.

The resistor elements I03 to I26, inclusive, as shown in Fig. 1 of the drawings, are connected in series-circuit relationship and the alternate junction points therebetween are connected to the contact pieces I3I and I32 in the order of the disposal of these contact pieces about the axis of the shaft 520. As thus arranged two resistor elements are connected in series between each adjacent pair of contact pieces. The purpose of using two series-connected resistor elements instead of a single element of higher resistance is to permit resistance matching such that the resistance connected between each adjacent pair of contact pieces is exactly that required to proelements of 450 and 550 ohms, respectively, may be used. In short, the elements may be selected in matched pairs such that the exact desired values of resistance between the different pcirs of contact pieces may be obtained.

The resistor elements M38, ltd, ltd, etc., are supported between the panel end the solder ing tails of the contact pieces Hill and H92. Thus the end of one lead-in wire to the resistor who is soldered to the soldering tell of the contact piece little and the other lead-in wire to this rc-= sister is passed through on opening in the penei tltlll. Similarly, the end of one iced-in wire to the matching resistor element ltlbh is soldered to the soldering tailor the contact piece i322 and the other leechin wire to this element is passed through an opening in the panel fltlil. ends of the wires which extend from the two elements who and W527 through the odiecent openings in the panel are twisted end. soldered. rugged supporting structure tor the elements is provided.

For the purpose of accurately controlling the movement of the shaft so that, regercliess of the setting thereof, the wiper [128 is accurately positioned to engage one of the contact pieces 83% or the wiper is positioned eccuretely to engage one of the content pieces 532, o. cumming arrangement comprising the panel or plate 508 and e. cooperating cumming element E589 rigidly secured to the shaft (529, is provided. More spe cificelly, the plate is provided with 9. number of openings dilSc therethrough which are conceh tricelly disposed about the axis of the shaft 528 end ore radially aligned with thecontoct pieces 853i and 632 carried by the panels hill and 582. The sections or this plate separating the open= ings are filled out or raised to provide coin nring surfaces over which the cam finger bite; of the cumming element 5 it! is adopted to ride as the shaft is rotated from. one position to st succeeding position. More specifically, the element 5th is in the form of a steel plate con= structed from fiat spring steel stock, and the com finger Eiliiez comprises a. bent-out portion of the plate having a rounded edge which is edepted to ride over the raised cumming surfaces between the openings beta, and bridges one of these openings each time the shaft 5% is adjusted to a. desired setting. With this who; I. arrangement, the shaft 528 can only be'operated in c step-bye step manner since the tension of the element M 9 is sufiiclent to rotate the shaft Mil until the cumming finger -5l9a bridges the nearest opening beta in the event the shaft is operated to a position lying between two of these settings.

From the above explanation it will be'understood that the operating shaft 520 is Journaled for rotation in the two panels 50! and 502 and also in the plate 503. This shaft is also journaled in a sleeve member 523 which is fixedly secured to the plate 503 and is threaded to receive an assembly nut 521. The arrangement for mounting the device upon the sub-panel 3M comprises a U- shaped mounting bracket 52l having its legs secured to the panel 8M by means of assembly screws and its central web drilled to receive the sleeve 523. The central web portion 01' the bracket piece MI is clamped between a spacing collar 522 which abuts the surface of the panel 508 and a lock washer 528 as the assembly nut 521 is screwed on the threaded sleeve 523. In order to maintain exact alignment between the radlal positions of the two panels 50! and 502 which carry the contact pieces I89 and I32 and the front panel ilttl upon which a portion of the indicating errengement referred to above is inscribed or mounted. an aligning pin (tilt is provided which extends through registering openings 5215 and 52b in the plate 5% end the bracket piece 526, respectively, and is press-fitted into a. third opening through the collar 622.

R1 the purpose of manually setting the rheostst W2 to any desired position, the shaft 52b is extended through openings provided in the two panels wt and tilt and is equipped at its outer end with s. lmob i323. To indicdte the relation ship that exists between the ground speed of the credt from which the bombs are to be dropped and the spacing intervals between on the objective for any particular setting of the rheostet, the lndicetting arrangement illustrated in Figs. l and 6 or the drawings h provided. This urrengement includes an index or indexing plate urrsnged on the outer surfioce of panel This index comprises logarithmically sceled in elicits. designating the intervals between bomb hits in feet and is arranged to cooperate with on his deizing element sealed at its outer peripheral edge with numerically defined indlcie of the grotmd speed of the craft in knots per hour. The element 'ltlb' is arranged to be driven from the shaft 5% through c. gear train which comprises c. driving gear and e, driven gear having predetermined ratio therebetween. More specifically, the gear is mounted for rotation with the shaft 526 and is positioned to rotate between the two panels and tilt; the gear bill is provided with a. hub di-ltb journeled in on opening provided in the outer panel the and with o rcerwerdly disposed hub title jourhuled in an eligned opening provided in the sub-panel 3M; and the indexing plate 6% is mounted upon the outer fist surface or the hub 53th by means of assembly screws E5532.

In considering the manner in which the illustruted apparatus is utilized to control the bomb relecse mechanism its, it may first be assumed that this mechanism is to be selectively controlled by the bomberdier of on aircraft in which the equipment is installed to release bombs from this craft selectively one at a. time. In such case, the master switch 958a is operated to its closedcircuit position; the switch ltd is operated to its select position wherein the contact springs its thereof are closed; and the counting device Ht is preset to the predetermined oil-normal position which corresponds to the number of bombs that are to be dropped. In order to preset this device. the knob MI is actuated to rotate the wheels ill and H4 so that the pin H2 is moved to the oil-normal position corresponding to the number of bombs to be released, this number being indicated by th coincidence of the pointer I8Ia with one of the indicia of the scale 403. As the pin I I2 is moved away from its normal position, the contact springs I13 are moved into engagement to prepare a circuit for supplying current to the input side of the vibrator I65 and to prepare the operating circuit for the locking relay I40.

with the apparatus thus conditioned for operation, the button or key control switch I 61 may be selectively operated by the bombardier of the aircraft to efl'ect the release of the bombs at any desired intervals. Each time the contacts of this switch are closed a. circuit is completed through the contact springs vI I3 for energizing the primary windings of the vibrator I65 and the winding of the locking relay 0 from the current source I88. In operating, the relay I40, at its contacts I43, closes an obviouscircuit for energizing the signal lamp I31. when voltage is applied to the input side of the vibrator I85 the normal rated output voltage appears across the output terminals I85b thereof to energize the pulsing relay I50 in a circuit which includes the contacts I63 and the resistor I64. In operating, the relay I50 closes its contacts II to complete a circuit including the source I88 for transmitting a current pulse to the bomb release mechanism I85, whereby this mechanism is actuated to release a bomb. At its contacts I54, the relay I50 completes an obvious circuit for energizing the stepping magnet I15. Incident to the operation of this magnet, the associated pawl mechanism is operated to rotate the wheels HI and I14 in a direction such that the pin I12 is moved one step nearer its normal position. When the contacts of the switch I81 are opened, the

relay I40, the signal lamp I31, the vibrator I65 and the pulsing relay I50 are all deenergized in an obvious manner. The relay I50, in releasing, opens its contacts I5I to terminate the current pulse transmitted to the bomb release mechanism I85. At its contacts I54, the relay I50 deenergizes the stepping magnet I15 of the counting device I10, whereby the pawl mechanism controlled by this magnet is released under the control of the leaf spring I80. In this regard it is noted that the suppressor circuit comprising the resistor 82 and the condenser I83 connected in shunt with the contacts I64, serves to protect these contacts against arcing and pitting during the opening and closing of the same. The condenser I84 is similarly connected in shunt with the contacts I5I to protect these contacts against arcing and pitting during the make and break periods thereof. The above-described operations are repeated each time the contacts of the switch I 61 are closed and then opened. From this explanation it will be understood that a current pulse is transmitted to the mechanism I85 to eiiect the release of a bomb each time the relay I50 operates, and that the pin I12 of the counting device I is moved one step nearer its normal position each time the contacts of the switch I61 are closed. After a predetermined number of operations of this switch, the pin I12 of the counting device I10 is rotated back to its normal position wherein the contact springs I13 are moved out of engagement. Following the disengagement of these contact springs further operation of the switch I61 is without eiIect to cause the operation of the two relays I40 and I50.

In utilizing the apparatus to control the bomb release mechanism so that a train of bombs is automatically released thereby, the counting device I10 is operated to the setting corresponding to the desired number of bombs in the train; the rheostat I02 is adjusted to the position corresponding to the desired spacing interval between hits for the expected ground speed of the craft during the bombing operation; the power switch I 68a is operated to its closed-circuit position; and the switch I60 is operated to its train position wherein the contacts I8I and I62 are closed. With the switch I68a closed and the switch I60 operated to its train position, an obvious circuit including the current source I68 is completed for energizing the cathode heater I00h of the control tube I00 in parallel with the signal lamp I31. It is noted in this regard that the heater I00h should be energized at least a full minute before the bombing operation is started.

After the above-described operations are performed, the switch I81 may be operated to initiate the release of the train of bombs. When the contacts of this switch are closed, a circuit is completed through the contact springs I13 for energizing the locking relay I40 and the primary windings of the vibrator I85 in parallel. In operating, the relay I40 closes its contacts I43 to complete a locking circuit Ior itself, this circuit extending from the positive terminal of the source I68 by way of the switch I88a, the contacts I82 and I43, the contact springs I13, and the winding of the relay I40 to the negative terminal of the current source. After this circuit is completed, the primary windings of the vibrator I65 are also energized in a circuit which includes the contacts I13, I 43 and I62. Accordingly, the switch I61 may be released without interrupting or terminating the bomb release operation in progress. At the time the switch I61 is operated, the condenser I34 is short-circuited over a path which includes the contacts I53 and the encircuited resistance of the rheostat I02. The cathode i000 and the control grid I00g are therefore at substantially the same potential.

When the primary windings of the vibrator are energized and the rated output voltage appears across the output terminals I65b of the vibrator, this voltage is positively applied to the screen electrode I00s of the tube I00 over a path including the resistor I39, and the winding of the relay I50 is energized by the space current flow through the tube I00. More specifically, the circuit for energizing this relay now extends from the positive output terminal l65b of the vibrator I65 by way of the winding of the relay I50, the contacts I6I, the space current path between the anode I00a and the cathode I00c of the tube I00, and the encircuited section IOIa of the biasing resistor IOI to the negative output terminal of the vibrator I65. When thus energized the relay I50 closes its contacts I5I to transmit a current pulse to the bomb release mechanism I85. At its contacts I54, the relay I50 closes the operating circuit for the stepping magnet I15, whereby the counting device I10 is operated to count the current pulse transmitted to the bomb release mechanism. At its contacts I53, the relay I50 opens the path short-circuitlng the condenser I34. At its contacts I52, the relay I50 bridges the condenser I34 across the encircuited portion IOIa.of the biasing element IOI in series with the encircuited resistance of the rheostat I02.

After the condenser I34 is thus bridged across the resistor section I 0Ia, the voltage drop appearing across this resistor section as the result of the space current flow through the tube I00 causes a charging current to be delivered to the condenser through the encircuited resistance of the rheostat I02. As this condenser is charged, the voltage thereacross approaches a value equaling that of the voltage drop across the resistor section I 0Ia. In this regard it will be understood that the rate of the voltage build-up across the condenser I34 is determined by the amount of resistance included in the charging circuit, which resistance serially includes the encircuited section IOIa oi the resistor IM and the encircuited resistance of the rheostat I02. Thus if the series resistance of this circuit is low, the voltage across the condenser I34 will rapidly be increasedto a value approaching that of the voltage drop across the resistor section IOIa. On the other hand, if the series resistance of this circuit is high a relatively much longer time inaccuser terval will be required for the voltage across the condenser R3 3 to approach the voltage drop across the resistor section illld. It will be noted that the charging current traverses the condenser Mi l in a direction such that the resulting voltage thereacross biases the control grid will? negatively with respect to the cathode Hilde. As this bias voltage isincreased, the space current flow through the tube ltd is decreased to decrease the voltage drop across the encircuited section itiia of the biasing resistor ibi and thus lower the charging rate of the condenser 88 3. After a predetermined time interval, required for the condenser lid to be charged to-a voltage some what less than the voltage drop across the resistor section it in, the space current flow through the tube lid is lowered to a value such that the relay 65d is insciently energized to remain operated. The relay 55b accordingly restores.

In releasing. this relay open its contacts lei to terminate the current pulse transmitted to the bomb release mechanism B85. At its contacts 95s, the relay ice deenergizes the stepping magnet iii of the counting device in. At its contacts 852, the relay ill! opens the above-described charging circuit for the condenser 4. At its contacts in, the relay H80 completes the proviously described circuit for discharging the condenser i34 through the encircuited resistance of the rheostat 802. After this discharge path is completed the condenser M5. starts to discharge through that portion of the rheostat resistance connected in shunt therewith, and as the condenser dlscharges the voltage thereacross decreases. Incident to the decrease of this bias voltage between the control grid mug and cathode illllc of the tube ltd, the space current flow through the tube is increased to increase the energization of the pulsing relay ibfi. Here again the rate of decay of the voltage across the condenser we is determined by the amount of rheostat resistance connected in shunt therewith. If the value of this resistance is low, the condenser ltd is rapidly discharged. 0n the other hand, if the value of this resistance is high the condenser 086 is only slowly discharged. It will be understood in this regard that the rate of discharge of the condenser its determine the we. interval required for the space current flowing through the tube to rise to a value suflicient to cause the reoperation of the pulsing relay led. en this value of space current is reached, the relay lbil reoperates to perform the functions described above. From this point on the above-described circuit control operations reoccur until such time as the pin iii of the counting device i'ld is driven back to its normal position under the control of the stepping magnet H5. In this regard it will be understood that the bomb release mechanism lob operates to release a bomb each time a current pulse is transmitted thereto under the control of the pulsing relay lbd.

When the pin H2 is returned to its normal position, the contact springs H3 controlled thereby are disengaged to cause the deenergization of the vibrator I65 and the relay M0 in an obvious manner. The relay I40, in restoring, opens its contacts I43 further to interrupt its locking circuit and the parallel circuit for energizing the primary winding of the vibrator I85. When this vibrator is deenergized the output voltage thereof is reduced to zero to cause a cessation in the space current flow through the tube are and thus effect the release of the pulsing relay I59, It

till

' resistance.

32 will be understood. therefore, that the operation oi the illustrated apparatus to transmit cent impulses to the bomb release mechanism Mill is terminated when the control pin lid oil the counting device lid is returned to its normal position. In order to deenergize the signal in llll it is necessary to restore the hey Hill to its normal position wherein the contacts 586 and 062 thereoi are respectively disengaged From the above explanation it will be under stood that the periodicity of operation oi the pulsing relay Gilli is deter-1: by the time constants of the circuits for charging and dis charging the condenser B86. It will also be un derstood that by suitable operation of the knob 0&8 to adjust the wipers I25 and lot along the contact pieces lei and 682, any desired portion of the rheostat resistance may m included in these circuits to change the time constants of these circuits accordingly. More specifically, as the encircuited resistance of the rheoatat i0! is increased to increase the time constants oi the charging and discharging circuits, the charging and discharging rates of the condenser E34 are lowered to decrease the periodicity at which the pulsing relay IE0 is operated and released. Conversely, as the encircuited rheostat resistance is lowered to decrease the time constants oi the charging and discharging circuits, the rate of charge and discharge of the condenser B34 is raised to increase the periodicity at which the pulsing relay m is operated and released. It has been found from actual tests that a substantially linear relationship exists between given increments of change in the encircuited rheostat resistance and the resulting increments oi change in the periodicity of operation of the pulsing relay ltd. In other words, changes in the pulsing rate of this relay are directly proportional to changes in the encircuited rheostat In the illustrated arrangement, the increments of resistance inserted in the con denser charging and discharging circuits as the rheostat is operated step-by-step from its low resistance setting toits high resistance setting are progressively decreased at each step, which means that thebomb interval spacing for a given ground speed of the craft is non-linearly relatedv to the difierent positions oi the rheostat control knob lbs and the erent positions of the indexing plate 495. In the indicating arrangement comprising the scale 404 and the scale carried by the indexing element Mill, the diflerences in the changes of rheostat resistance at different steps thereof are accounted for by utilizing logarithmically spacedscale indicia, which in the spacings therebetween, are so related to the pulsing rate for each setting of the rheostat as to provide an accurate indication of the relationship between bomb hit spacing and ground speed of the craft. The initial calibration of the scale M4 may be accurately determined by calculating, for a given ground speed of the craft, the pulsing rates of the relay 550 which are required for the different bomb hit spacings, and then calculating or experimentally determining the increments of rheostat resistance that are required between the diflerent contact pieces of the rheostat to provide the desired pulsing rate at each setting of the rheostat. From the measured pulsing rate for each setting of the rheostat, the bomb hit spacing may then easily be ascertained and suitably identified in the scale 404 opposite the mark of the scale 40! which desigates the ground speed at which the scale 404 is being calibrated. After the markings of the scale 408 are thus determined for one ground speed. the markings of the scale 40! may readily be determined, because of the direct ratio which exists between bomb hit spacing and ground speed of the craft.

As indicated by the above explanation, the resistance value of the resistor section IOIa determines the magnitude of the average current flow through the winding of the relay I50 during the pulsing contact make periods thereof and hence the extent of each contact make period. This arrangement forms a convenient vehicle whereby the ratio of the make and break periods of the pulsing contacts I5I, controlled by the relay I50,

7 maybe varied. Thus by decreasing the resistance" value of the resistor section IOIa, the make periods of the contacts I5I are increased to increase the ratio of the make to break periods. Conversely, by increasing the resistance of the resistor section I Ia each make period of the contacts II may be decreased to lower the ratio of the make to break periods.

As previously indicated, so long as the potential positively applied to the screen electrode I00s of the tube is maintained substantially constant, full control of the magnitude of space current flow through the tube I00 is obtained by varying the bias on the control grid I00g thereof, regardless of wide variations in the voltage appearing across the output electrodes I65b of the vibrator I85. On this point it has previously been indicated that the voltage of the source I88 may vary from its rated value by as much as 10% plus or minus. Such variations in the voltage applied to the input terminals of the vibrator I 85 will, in the usual commercial type of vibrator, result in substantial changes in the voltage across the output terminals thereof. In the illustrated arrangement, however, such variations in the voltage of the source from which the screen potential is derived do not materially change the applied potential of the screen electrode I00s. Thus immediately the output voltage appears across the terminals I85b of the vibrator I65, the discharge tube I83 is ionized. As this voltage tends to increase, due to an increase in the voltage across the terminals I851), the current traversing the space current path of the tube I88 increases to increase the voltage drop across the resistor I 38. Conversely, as the voltage across the output terminals I 85b of the vibrator I 65 decreases, the

current drawn by the tube I38 through the resistor I38 is decreased. Due to this action the voltage across the electrodes of the tube I38, i. e., that positively applied to the screen electrode I00s, is stabilized at a predetermined value which may be equal to the rated screen voltage of the tube. As a result, those variations in the voltage applied to the anode I00a of the tube through the winding of the pulsing relay I50, do not deprive the control grid I00g from full control of the space current flowing through the tube. Thus the periodicity of operation of the pulsing relay I50 is rendered substantially independent of variations in the voltage appearing across the output terminals of the vibrator I65.

From the above explanation it will also be un derstood that wide changes in the temperature of the apparatus tend to vary the rate at which impulses are produced thereby. Thus, the measured resistance of the resistor elements I03, I04, I05, etc., included in the timing circuit, may vary as much as twenty-two percent over the operating temperature range. These elements all have a positive temperature coeflicient of resistance.

Other factors tending to contribute to a change in the pulsing rate with ambient temperature variations are changes in the resistance of the re- 5 sistor IN and the winding of the relay I50, and relative displacement of the elements of the tube I00. The net effect of the various factors is the same as that obtained by using a rheostat I02,

the elements of which have a substantial positive coeflicient of resistance, 1. e., the pulsing rate increases with a decrease in the ambient temperature and vice versa. This effect is offset by the action of the resistor I02 having a negative temperature coemcient of resistance and hence the effect of decreasing the pulsing rate of the apparatus as the ambient temperature decreases.

has been found that by using a resistor I02 of Othe character indicated and having the proper resistance value, the pulsing rate of the apparatus is substantially unafiected by wide variations in the temperature of the apparatus.

Referring now more particularly to Fig. 2 of the drawings, the apparatus there illustrated is substantially similar in construction and arrangement to that shown in Fig. 1 and described above. In fact, the apparatus as mechanically shown in Figs. 3 to 6, inclusive, of the drawings may be wired either in accordance with the circuit of Fig. 1 or that of Fig. 2, corresponding reference characters differing only in the hundreds digit being used to identify corresponding parts of the two circuits. It will be noted that in the Fig. 2 arrangement the voltage regulating gaseous discharge tube 238, which is provided for maintaining the screen potential 200s of the control tube 200 constant, is connected directly between this electrode and the associated cathode 2000. This arrangement has the advantage that the constancy of the potential applied to the screen electrode is measured as between this electrode and the cathode rather than between the screen electrode and ground. Thus variations in the space current flow through the cathode resistor I occasioned by variations in the bias applied to the control grid 200g do not alter the potential difference between the screen electrode 200s and the cathode 200e, Accordingly, the magnitude of space current flow through the tube 200 is determined substantially entirely by the bias applied to the control grid 2009.

It also will be noted that in the Fig. 2 arrangement a voltage divider 235 is provided which is connected between the cathode 2000 and the grounded negative output terminal 205b of the vibrator 265. The adjustable tap or wiper of this voltage divider is connected to the wipers of the rheostat 202 so that a variable portion of the voltage drop across the resistor 235 is normally impressed across the electrodes of the bias determining condenser 234.

In considering the manner in which the circuit arrangement illustrated in Fig. 2 functions, it may first be assumed that the bomb release mechanism is to be controlled to release bombs selectively one at a time. In such case, the power switch 258a is operated to its closed-circuit position and the switch 260 is operated from its illus trated normal position to its select position wherein the contacts 282a, 2621) and 2620 are r spectively engaged. After the power switch 258a is closed, and when the switch 260 is operated to its select position, a circuit including the contacts 262a is completed for energizing the primary windings of the vibrator 265 in parallel with the filament of the signal lamp 231. The energize.-

tion of this lamp provides a signal that the switch 22cc occupies one of its two ofi-normal positions. When energizing current is delivered to the primary windings of the vibrator 269, an output voltage appears across the output terminals 2656b which serves to energize the relay 25b in a circuit which includes the resistor 289' and the engaged key contacts 2820. In operating, the relay 258i closes its contacts 2th to prepare the available circuit for transmitting current impulse to the bomb release mechanism 285. At its contacts 254i and 255, the relay 25h prepares the operating circuit for the stepping magnet 2W6 oi the counting device Zldand one of the circuits tor energizing the relay 2%.

'With the apparatus thus conditioned for operation, the button or hey-controlled switch 2m may be selectively operated by the bombardier of the aircraft to effect the release or the bombs at any desired intervals. Each time the contacts of this switch are closed, a circuit is completed through the contacts 28% for energizing the look-- ing relay 2% from the current source 288. In operating, the relay 240 closes its contacts 2" to transmit a current pulse through the contacts 26! to the bomb release mechanism 28!, whereby this mechanism is actuated to release a bomb. The remaining circuit switching operations performed by the relay 240 are of no eflect in the case under consideration wherein the switch 260 occupies its select position. When the contacts of the switch 261 are opened, the relay etc is deenergized in an obvious manner. In releasing, this relay opens its contacts MB to interrupt the current pulse transmitted to the bomb release mechanism 285. In this regard it is noted that the condenser 2M shunting the series-connected contacts 2 1i and 2M serves to protect the contacts 2M against arcing and pitting as these con tacts are opened and closed to transmit current impulses to the bomb release mechanism. The above-described operations are repeated each time the contacts of the switch car are closed and then opened. From this description, it will be understood that a current impulse is transmitted to the release mechanism 285 each time the switch it? is operated and then released to cause the operation and release of the relay Md. This mechanism responds to each received impulse by releasing a single bomb. After the desired number of bombs have been dropped, the switch 2% may be restored to its normal position to cause the deenergization of the vibrator 265, the relay 250 and the signal lamp 23F.

In utilizing the apparatus illustrated in Fig. 2 of the drawings to control the bomb release mechanism 285 so that a train of bombs is automatically released thereby, the power switch 288:: is operated to its closed circuit position; the counting device 27B is operated to the setting corresponding to the desired number of bombs in the train; the rheostat N2 is adjusted to the position corresponding to the desired spacing interval between bomb hits for the expected ground speed of the craft during the bombing operation; and the switch 260 is operated to its train position wherein the contacts 265a, 26"; and Rio are.

respectively engaged. With the power switch 268a closed and the counting device '210 preset so that the control'pin 212 thereof occupies an off-normal position, a circuit including the contacts 213a is completed for energizing the cathode heater 20th, the signal-lamp 231, and the primary windings of the vibrator 265 in parallel. It is noted in this regard that the cathode heater 260);

END

ing resistors 285 and 2M in parallel. When thus energized the relay sec closes its contacts 256 to prepare the circuit for transmitting current impulses to the bomb release mechanism 285 and. at its contacts 2&6 and 2%, prepares the operating circuit for the stepping magnet 275 oi the counting device 2% and a circuit for energizing the relay 26c. At its contacts 2%, the relay 256i opens a point in the circuit over which the condenser 233 may be discharged. At its contacts 252, the relay 25c prepares a circuit ior charging this condenser to a value approaching that appeering across the resistor section 20m and re- 3131:1118 from space current now through the tube Alter space current flow through the tube has been initiated in the manner explained above, the space current traversing the resistor section row of the biasing element 20! produces a voltage drop across this element which is impressed across the voltage dividing resistor 235. A portion of this voltage, i. e., that appearing across the resistor section 2380, is impressed across the electrodes of the condenser :34 through the encircuited resistance of the rheostat 202. After a short time interval, and before the bomb release switch 2W is operated, the condenser 28 3 is charged to the full value of the voltage across the resistor section 23cc. This voltage, it will be noted, is negatively applied to the control grid titty or the tube 2% to reduce the space current v flow through the tube. By adjusting the wiper along the voltage dividing resistor 285, the extent or this bias voltage may be varied at will. Preferably this adjustment is so carried out that the magnitude of the space current flowing through the tube 2% only slightly exceeds that required to operate the relay rec after this relay has been released. The purpose or thus preliminarily biasing the control grid who by charging the condenser 236 to a predetermined value is that of reventing the first release period of the relay 2%,

- following the operation oi the bomb release switch 267, from being unduly long.

After the above-described operations are com= pleted, the bomb release switch 2% may be operated to initiate the release of the train of bombs. When the contacts of this switch are closed a circuit is completed through the contacts 269! and 2113b for energizing the locking relay 240 from the current source 268. In operating, the relay 2481i closes its contacts to complete a looking circuit for itself which extends from the positive terminal of the source 288 by way of the power switch 28811, the contacts 26in, 263 and 213b, and the winding of the relay 0 to the negative terminal of the source 268. A- parallel branch of this circuit extends through the contacts 255 and 245. After this locking circuit is established, the switch 261 may be released without interrupting or terminating the bomb release operation in progress. At its contacts I, the relay 240 closes the above-described circuit for transmitting a current pulse to the bomb release mechanism 285. At its contacts 246, the relay shunts the contact springs 213a oi the counting device to complete obvious multiple circuits for energizing the cathode heater 20011., the signal lamp 231 and the primary windings of the vibrator 265. At its contacts 244, the relay 240 completes the prepared operating circuit for the stepping magnet 215, this circuit extending from the positive terminal of the current source 288 by way of the power switch 268a, the contacts Mile and 243, the winding of the magnet 215, and the contacts 254 and 244 to the negative terminal of the source 268. When its operating magnet is thus energized, the counting device 210 is operated to count the current impulse transmitted to the bomb release mechanism 285.

At its contacts 242, the relay 240, in operating, completes the previously mentioned circuit for charging the condenser 234 to a voltage sufllcient to cause the release of the pulsing relay 250. Thus when these contacts are closed, the condenser 234 is bridged across the resistor section 20la of the biasing element 20l over a path which includes the encircuited resistance of the rheostat,

202 and the contacts 252, 242 and 28la. It will be noted that incident to this switching operation, the lower portion 235!) of the resistor 235 is short-circuited and the resistor sections 235a and 201:: are connected directly in parallel. The resistance value of the resistor section 235a is, however, several times that of the resistor section 201a, and hence the time constant of the condenser charging circuit is not materially influenced by the resistor section 235a. When the above-described charging circuit is completed, the voltage across the condenser 234,1. e., the bias voltage negatively applied to the control grid 200g, starts to rise at a rate determined by the setting of the rheostat 202. Here again if the encircuited resistance of the rheostat 202 is low, such that the series resistance of the charging circuit is small, the voltage across the condenser 234 will rapidly rise to a value approaching that of the voltage drop across the resistor section 20la. On the other hand, if the encircuited resistance of the rheostat 202 is high, a relatively much longer time interval will be required for the voltage across the condenser 234 to rise to a value approaching the voltage drop across the resistor section 201a. After a, predetermined time interval, determined by the time constant of the charging circuit and hence by the setting of the rheostat 202, the bias voltage across th condenser 234 is increased to a point such that the space current flow through the tube 200 is insuflicient to retain the pulsing relay 250 in its operated position. This relay accordingly restores.

In releasing, the relay 250 opens its contacts Hi to terminate the current pulse transmitted to the bomb release mechanism 285. At its contacts 255, the relay 250 opens one of the locking circuits for the relay 240. At its contacts 254, the relay 250 deenergizes the stepping magnet 215 of the counting device 210. At its contacts 252, the relay 250 opens the above-described charging circuit for the condenser 234. At its contacts 253, the relay 250 completes an obvious circuit for discharging the condenser 234 through the encircuited resistance of the rheostat 202. After this condenser discharge circuit is established, the condenser 234 starts to discharge through that portion of the rheostat resistance connected in shunt therewith, and as it discharges the voltage thereacross decreases. Incident to the decrease of this bias voltage between 18 the control grid 200a and the cathode 2000 of the tube 200, the space current flow through the tube rises to increase the energization of the pulsing relay 250. Here again, the rate of decay of the voltage across the condenser 234 is determined by the amount of rheostat resistance connected in shunt therewith. Thus if the value of this resist- .ance is low the condenser 284 is rapidly discharged. On the other hand, if the value of this resistance is high the condenser 234 is only slowly discharged. It will be understood in this regard that the rate of discharge of the condenser 284 determines the time interval required for the space current flowing through the tube 200 to rise to a value sufllcient to cause the reoperation of the pulsing relay 250. When this value of space current is reached, the relay 250 reoperates to perform the functions described above. From this point on the above-described circuit control operations reoccur until such time as the pin 212 of the counting device 210 is driven back to its normal position under the control of the stepping magnet 215. It will be understood in this regard that the bomb release mechanism 285 operates to release a bomb each time a current impulse is transmitted thereto under the control of the pulsing relay 250.

When the relay 250 is operated to transmit the current pulse required for effecting the release of the last bomb of the train, it recloses its contacts 255 to shunt the contact springs 21% of the counting device 210 and thus establish the above-described multiple locking circuit for the relay 240. Thus the relay 240 is prevented from releasing to prematurely terminate the current pulse being transmitted to the bomb release mechanism 285, in response to the separation of the contact springs 21% which occurs shortly after the last operation of the relay 250. In this regard it will be noted that when the counting device 210 is operated to count the last current pulse transmitted to the bomb release mechanism 285, the pin 212 is returned to its normal position to efiect the disengagement of the contact springs 21% and 213a, respectively. At the contact springs 213a, the initially completed circult for energizing the primary windings of the vibrator 265 in parallel with the filament of the lamp 231 and the cathode heater 20071., is opened. This circuit is, however, held closed at the contacts 246 of the locking relay. When the relay 250 thereafter releases to terminate the last current pulse transmitted to the bomb release mechanism 285, it opens its contacts 255 to interrupt the only remaining locking circuit for the locking relay 240. The relay 240 now restores and impulse transmission to the release mechanism 285 is terminated. In releasing, this relay opens its contacts 248 to deenergize the cathode heater 20071., the lamp 231 and the primary windings of the vibrator 265. Following the release of the relay 240, the key 260 may be returned to its normal position completely to restore the apparatus to normal, or the counting device 210 may be reoperated to a desired setting and the bomb release key 261 operated to initiate the release of another train of bombs. The manner in which these operations may be performed, and the operations resulting therefrom, will be clearly apparent from the preceding explanation.

From the above description it will be understood that the efl'ect of varying the encircuited resistance of the rheostat 202 is exactly the same as that obtained by varying the encircuited resistance of the rheostat 102 in the Fig. 1 circuit arrangement.

control circuit by said control device,

amass:

19 This eflect, it will be recalled, is that of changing the periodicity at which thecurrent pulses are transmitted to the bomb release mechanism "I. It is also pointed out that the resistor 20!, having a negative temperature coeflicient oi resistance, functions in the same manner as the corresponding resistor I02 or the Fig. 1 arrangement, in that it prevents the pulsing rate oi the apparatus from being substantially altered as a result of wide variations in the temperature or the apparatus. It will be noted further that the effect of varying the resistance of the encircuited portion Illa oi the biasing resistor 2M is also the same as that realized by changing the setting oi! the adiustable resistor liil provided in the Fig. 1 circuit arrangement. Thus it will be apparent that by changing the setting of the adjustable resistor 20! the ratio between the make and break periods of the pulsing contacts "I may be varied as desired.

While two embodiments oi! the invention have been disclosed, it will be understood that various modifications may be made therein which are within the true spirit and scope of the invention.

What is claimed is:

1. In a system for transmitting impulses over a control circuit, an electron discharge tube including input and output electrodes and a screen electrode, an output circuit including" said output electrodes, a source of current and a control device for transmitting impulses over said control circuit, an input circuit for said tube including means for periodically operating said tube thereby to periodically operate said control device, a circuit for impressing at least a portion of the voltage of said source on said screen electrode. voltage regulating means for maintaining the voltage on said screen electrode substantially constant regardless of fluctuations in the voltage of said source, thereby to prevent the voltage fluctuations of said source from substantially altering the periodicity of operation oi said control device, and means including an'impulse counting device controlled by the operation oi! said control, device tor arresting theperiodic operation of said tube after a predetermined numbers! impulses are transmitted over said control circuit bysaid control device.

2. In a system for transmittingimpulse's over: 1

a control circuit, an electron discharge tube in"-v cl'uding input and output electrodes and a screen;

electrode, an output circuit including said output electrodes, a source or current and a control device for transmitting impulses over said .control circuit, 'an input circuit for said tube including. means ,iorperiodlcally operating said tube thereby to periodically operate 'saidcontrol device, acircult-tor impressing atleast'a pcrtion-ot thevoltage of. said source on said screen electrode,1.volt-;

on. said screen electrode substantially, constant f r regardless of fluctuations i'nthevoltageof said 7 source, thereby to prevent thevoltage fluctuatlonsotsaid source from substantially altering-the periodicity of operation of said control device,= 'an impulse countingdevice adapted- "to be manually. preset to count any desired number of impulses and including means controlled-by the operation of said control device tor-counting each-impulse;

ageregulating means for'maintaining thevoltage' transmitted over said 'control circuit, and. means controlled .by. said counting deviceiorarresting theperiodic operation of said tube after the humher o'fim'pulses corresp nding to the; setting or,

said counting device are transmitted war said 3. In a system for transmitting impulses over a control circuit, an electron discharge tube including input and output electrodes and a screen electrode, an output circuit including saidoutput electrodes, a source of current and a control device ior transmitting impulses over said control circuit, an input circuit coupled to said input electrodes and including means for periodically operatlng said tube thereby to periodical rate said control device, a circuit for impressing at least a portion or the voltage oi said source on said screen electrode, means comprising a gaseous discharge tube connected between said screen electrode and one terminal oi said source for maintaining the voltage on said-screen electrode substantially constant regardless of fluctuationsin the voltage of said source, thereby to prevent the voltage fluctuations of said source from substantially altering the periodicity of operation of said control device, and means including an impulse counting device controlled bythe operation of said control device for arresting the periodic operation of said electron discharge tube alter a predetermined number of impulses are transmitted 25 over said control circuit by said control device.

4. In a system for transmitting impulses over Ya control circuit, an electron discharge tube in. cluding input and output electrodes and a screen electrode, an output. circuit including said output so electrodes, asource of current and a control device for transmitting impulses over' said control circuit, an input circuit coupled to said input electrodes and including means for periodically operating said tube therebyto periodically operate said 35 controldevi'ce, a circuit for impressing at least a portion 0! the voltage or said source on said screen electrode, means comprising a gaseous discharge tube connected between said screen electrode and one terminal of said source for maintaining the yoltage ,on said screen electrode substantially constant regardless of fluctuations in the voltage of said source, thereby to prevent the voltage fluctuations of said source fromsubstantially aldevice,jan impulse counting device adapted to be manually preset to count anydcsired number or impulses and including means controlled by the operation oi" said control device .!or counting each transmitted over said control circuit, and means controlled by said counting device for arresting the periodic operation or said electron dis- ,c'liargeftube after the numbersor impulses corre- Im ld ngto'the setting 01 said. countingde'vice over said control. circuit by said contr l-seme- 'fi jIn a system (or transmitting impulses over I ,pontrol circuit, an electron discharge tube inmcludingfa cathode, an anode, a screen electrode 'afi'control electrode, a cathode biasing e'leoutput'circuit, said cathode and anode, ,said biasing; element, a source oi!v current and 'anielectromagneticcontrol device all serially inc'lud'edin said output; circuit, said-control device operated-over said outputcircuit for transmitimpulsesover said control circuit, an input "trol electrode and including means controlled by said device controlling said input circuit to cause eriodic: operation of said device, a circuit for at-leastaportion oi the voltage of tering the periodicity of operation or said control Y Qircuitlcoupledbetween said cathode and conscreen electrode substantially constant regardless of fluctuations in the voltage of said source.

6. In a system for transmitting impulses over a control circuit, an electron discharge tube including a cathode, an anode, a screen electrode and a control electrode, an output circuit serially including said cathode and anode and a source of current, a circuit for impressing at least a portion of the voltage of said source on said screen electrode, a relay having a winding included in said output circuit and including front contacts and back contacts and impulsing contacts for transmitting impulses over said control circuit, means including a first biasing circuit connected to said control electrode having a first biasing potentialimpressed thereon for controlling said tube to pass suflicient current to said output circult to operate said relay, means including a switch for impressing a second biasing potential through said front contacts to said control electrode over a second biasing circuit to control said tube to pass insufiicient current to said output circuit to retain operated said relay, and means including a condenser connected to said control electrode for impressing a control biasing potential varying with time between said second biasing potential and said first biasing potential through said back contacts to said control electrode, whereby said relay is periodically operated, and means comprising a gaseous discharge tube connected directly between said screen electrode and said cathode for maintaining the voltage on said screen electrode substantially constant regardless of fluctuations in the voltage of said source.

7. In a system for transmitting impulses over a control circuit, an electron discharge tube including output electrodes and a control electrode, an output circuit serially including said output electrodes and a source of current, a relay having a winding included in said output circuit and including front contacts and back contacts and impulsing contacts for transmitting impulses over said control circuit, means including a first biasing circuit connected to said control electrode having a first biasing potential impressed thereon for controlling said tube to pass suflicient current to said output circuit to operate said relay, means including a switch for impressing a second biasing potential through said front contacts to said control electrode over a second biasing circuit to control said tube to pass insufiicient current to said output circuit to retain operated said relay, timing means including a condenser connected to said control electrode and adapted to be charged in accordance with said biasing potentials, and a discharge circuit' for said condenser including said back contacts and a portion of said second biasing circuit for varying withtime said biasing potentials impressed on said control electrode between said second biasing potential and said first biasing, potential, whereby said relay is periodically operated.

8. In a system for transmitting impulses over a control circuit, an electron discharge tube including output electrodes and a control electrode, a biasing element, an output circuit serially including said output electrodes, said biasing element and a source of current, a relay having a winding included in said output circuit and including front contacts and back contacts and impulsing contacts for transmitting impulses over said control circuit, means including a first biasing circuit connected to said control electrode having a first biasing potential impressed thereon for controlling said tube to pass sufiicient current to said output circuit to operate said relay, means including a switch for impressing a second biasing potential through said front contacts to said control electrode over a second biasing circuit to control said tube to pass insuflicient cur! rent to said output circuit to retain operated said relay, and means comprising a timing circuit connected to said ontrol electrode for impress ing a control biasing potential varying with time between said second biasing potential and said first biasing potential through said back contacts to said control electrode, whereby said relay is periodically operated and released.

9. In a system for transmitting impulses over a control circuit, an electron discharge tube including output electrodes and a control electrode,

a biasing element, an output circuit serially including said output electrodes, said biasing element and a source of current, a relay having a winding included in said output circuit and including front contacts and back contacts and impulsing contacts for transmitting impulses over said control circuit, means including said biasing element and a resistor serially connected between said biasing element and said control electrode for impressing a first biasing potential on said control electrode, thereby to control said tube to pass sufiicient current to said output circuit to operate said relay, means including a switch for impressing a second biasing potential through said front contacts and said resistor to said control electrode, thereby to control said tube to pass insuflicient current to said output circuit to retain operated said relay, and a timing circuit serially including a condenser, said resistor and said back contacts connected to said control electrode for varying said biasing potentials impressed on said control electrode between said second biasing potential and said first biasing potential, thereby cyclically to restore and operate said relay.

EDWARD S. PETERSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,209,380 Bell July 30, 1940 1,384,559 Giles et a1 July 12, 1921 2,071,958 Watrous, Jr Feb. 23, 1937 2,042,869 Smith June 2, 1936 1,959,010 Tellegen May 15, 1934 2,210,394 Branden Aug. 6, 1940 2,016,147 La Pierre et al. Oct, 1, 1935 2,132,264 King Oct. 4, 1938 1,946,615 Demarest Feb, 13, 1934 2,090,224 Noble Aug. 17, 1937 2,098,052 Lord Nov. 2, 1937 1,979,054 Sheer Oct. 30, 1934 2,188,159 Rockwood Jan. 23, 1940 1,936,692 Stoller Nov. 28, 1933 2,328,304. Sorensen Aug. 31, 1943 2,310,105 Michel Feb. 2, 1943 1,908,326 Demarest May 9, 1935 2,165,048 Gulliksen July 4, 1939 FOREIGN PATENTS Number Country Date 775,986 France Oct. 22, 1934 313,143 Great Britain May 16, 1930 408,625 Great Britain 1934 408,624 Great Britain Am. 9, 1934 

